Moisture-triggered 1,3,5-triazine-based Cu(II) molecular switch: a combined X-ray single-crystal and powder diffraction study

A solvothermal synthetic procedure has been exploited to prepare the new [Cu(3)L(NO(3))(6)](n) coordination polymer (1) by reaction of the polydentate N,N'-{2,4-di-[(di-pyridin-2-yl)amine]-1,3,5-triazine}ethylenediamine ligand (opytrizediam L) with copper(II) nitrate. 1 has been structurally characterized by means of the conventional X-ray single-crystal diffraction technique. It crystallizes in the monoclinic C2/c space group with a = 16.830(3), b = 20.701(4), c = 18.170(4) Angstroms, beta = 113.26(3) degrees, V = 5816(2) Angstroms(3), Z = 4. 1 consists of trinuclear Cu(3)L(NO(3))(5) units connected by means of a nitrato-O,O' bridge. The resulting chains are involved in weak interchain head-to-tail pi-pi stacking interactions. In the presence of moisture, 1 is readily converted into the hydrated [Cu(3)L(NO(3))(5)](NO(3)).H(2)O form (2). This second phase, monoclinic P2(1)/c, consists of isolated [Cu(3)L(NO(3))(5)](+) and (NO(3))(-) ions which accommodate water molecules in the crystal lattice. These subtle chemical and structural modifications accompanying the moisture-triggered 1-to-2 transformation have been demonstrated through a X-ray powder diffraction study. A thermodiffractometric analysis has evidenced that this solid-to-solid transformation is fully reversible, i.e., thermally induced dehydration of 2 restores 1. The analysis of the temperature dependence of the magnetic susceptibility for 2 has revealed very weak ferromagnetic interactions, consistent with the large Cu...Cu separation (ca. 7.5 Angstroms) in the trinuclear units.     

Structure-property correlations in polypropylene from metallocene catalysts: stereodefective, regioregular isotactic polypropylene

A series of MAO-activated C(1)-symmetric indenyl-ansa-dithienocyclopentadienyl-based zirconocenes have been used to produce isotactic polypropylenes of medium to high molecular weights, of different degrees of stereoregularity, and free from regioerrors. The effect of the presence of rr defects on the polymorphic behavior and mechanical properties of polypropylene is analyzed. The presence of rr defects induces crystallization of gamma form and of disordered modifications intermediate between alpha and gamma forms. A linear relationship between the amount of gamma form and the average length of isotactic sequences has been found. Samples with low concentration of rr defects, up to 3-4%, present high melting temperatures, in the range 160-130 degrees C, and behave as stiff-plastic materials; sample with higher rr content, in the range 4-6% and melting temperatures around 115-120 degrees C are highly flexible thermoplastic materials, and, finally, samples with concentration of rr defects in the range 7-11% and melting temperatures in the range 80-110 degrees C are thermoplastic elastomers with high strength. The fine-tuning of the chain microstructure, achieved by a tailored design of new metallocene catalysts, has allowed production of new polypropylenes having desired properties, intermediate between those of stiff plastic and elastomeric materials.     

Highly efficient stereoselective synthesis of d-erythro-sphingosine and d-lyxo-phytosphingosine

Starting from a single suitable functionalised epoxide, a highly efficient stereoselective synthesis of d-erythro-sphingosine and d-lyxo-phytosphingosine is described. The approach allows the formal preparation of all stereoisomers of these sphingoid structures.     

Analysis of the sinusitis nasal lavage fluid proteome using capillary liquid chromatography interfaced to electrospray ionization-quadrupole time of flight- tandem mass spectrometry

The nasal lavage fluids (NLFs) from four subjects with acute sinusitis were analyzed to investigate the amount of proteins expressed in this pathology at the beginning of the event (day 1) and after 6 days of treatment with antibiotics and a nasal steroid spray. The protein identification was performed with capillary liquid chromatography-electrospray-quadrupole time of flight-(LC-ESI-Q-TOF)-mass spectrometry. The samples collected on the first day contained high-abundant plasma proteins, such as albumin and immunoglobulins, glandular serous cell proteins (lysozyme, lactoferrin, and polymeric immunoglobulin receptor), epithelial keratins, and inflammatory cell proteins (myeloperoxidase, IL-16, and IL-17E). After six days of therapy, the complexity of the proteome was reduced to plasma proteins and lysozyme with no inflammatory markers. The presence of hemoglobin, however, suggested that significant squamous metaplasia with breaches in the epithelial barrier, or nasal steroid-related bleeding, had occurred. The proteomic approach presented here allowed us to identify, in the high complexity of acute sinusitis nasal secretions, the proteins that respond to a pharmacological treatment and that could be suitable as markers of this pathology.     

Multiple component approaches to C-glycosyl beta-amino acids by complementary one-pot Mannich-type and Reformatsky-type reactions

The development of new methods for the preparation of C-glycosyl beta-amino acid libraries with chemical and stereochemical diversity levels was investigated and the results are described herein. Two complementary one-pot three-component Mannich-type and Reformatsky-type synthetic strategies have been developed for the construction of chiral 3-amino propanoate fragments (eventually bis-substituted at C-2) directly linked to the anomeric carbon of pyranose and furanose residues. Both methods involved as the initial step the coupling of a sugar aldehyde to p-methoxybenzylamine but differed in the nucleophile (a d(2) synthon equivalent) which was successively added: a ketene silyl acetal (Mannich route) or a bromozinc enolate (Reformatsky route). Individual C-glycosyl beta-amino esters were isolated as single 3R diastereoisomers in fair to excellent yield (60-90%) and their structure assigned by NMR spectroscopy (Riguera protocol) supported by X-ray crystallography. A tentative explanation of the observed stereochemical outcome based on transition-state models is provided. A preliminary study on the synthesis of alpha,alpha-difluoro C-glycosyl beta-amino acids via a more traditional Reformatsky route is also reported.     

Formation of heterotopic metallacalix[n]arenes (n=3, 4, 6) containing ethylenediaminepalladium(II) metal fragments and 4,7-phenanthroline and 2-pyrimidinolate bridges. Synthesis, structure and host-guest chemistry

A multicomponent reaction involving ethylenediaminepalladium(II), 2-pyrimidinol derivatives (L) [L=2-pyrimidinol (a); 4-methyl-2-pyrimidinol (b); 4,6-dimethyl-2-pyrimidinol (c)] and 4,7-phenanthroline (4,7-phen) leads to the formation of heterotopic cyclic metallamacrocycles of the type [Pdn(en)n(mu-N,N'-L)m(mu-N,N'-4,7-phen)n-m](2n-m)+ [n=3, m=1 (3); n=4, m=2 (4); n=6, m=4 (5)]. These species can be obtained by different reaction pathways, including: (i) reaction of ethylenediaminepalladium(ii), L and 4,7-phen building blocks and (ii) reaction of the homotopic species [Pd4(en)4(mu-N,N'-L)4]4+ (1) and [Pd3(en)3(mu-N,N'-4,7-phen)3]6+ (2). The resulting heterotopic metallamacrocycles have been characterised by 1D and 2D 1H NMR spectroscopy. Additionally, species 3c and 4a have been studied by X-ray crystallography. The former one contains almost isosceles triangles of [Pd3(en)3(mu-N,N'-4,6-dimethyl-2-pyrimidinolate)(mu-N,N[prime or minute]-4,7-phen)2]5+ formulation, exhibiting a pinched-cone conformation. 4a contains a tetranuclear parallelogram [Pd4(en)4(mu-N,N'-2-pyrimidinolate)2(mu-N,N'-4,7-phenanthroline)2]6+, exhibiting a 1,3-alternate conformation. The host-guest properties of the here reported species have been studied, showing that they are able to interact with cationic as well as with anionic species.     

Quantification of the plant-derived hallucinogen Salvinorin A in conventional and non-conventional biological fluids by gas chromatography/mass spectrometry after Salvia divinorum smoking

A gas chromatography method with mass spectrometric detection is described for the determination of Salvinorin A, the main active ingredient of the hallucinogenic mint Salvia divinorum. The method was validated in plasma, urine, saliva and sweat using 17-alpha-methyltestosterone as internal standard. The analytes were extracted from biological matrices with chloroform/isopropanol (9:1, v/v). Chromatography was performed on a 5% phenyl methyl silicone capillary column and analytes were determined in the selected ion monitoring mode. The method was validated over the concentration range 0.015-5 microg/mL plasma, urine and saliva and 0.01-5 microg/patch in the case of sweat. Mean recoveries ranged between 77.1 and 92.7% for Salvinorin A in different biological matrices, with precision and accuracy always better than 15%. The method was applied to the analysis of urine, saliva and sweat from two consumers after smoking 75 mg plant leaves to verify the presence of the active ingredient of S. divinorum in human biological fluids as a biomarker of plant consumption. Salvinorin A was detected in urine (2.4 and 10.9 ng/mL) and saliva (11.1 and 25.0 ng/mL), but not in sweat patches from consumers.     

Synthèse et caractérisation du phosphate de hafnium comme échangeur d'ions

The preparation, crystalline structure, properties and behaviour of the hafnium bis (monohydrogen phosphate) monohydrate as a cationic exchanger have been studied. The crystalline product has been characterized by elemental analysis, X-ray Powder patterns, thermal analysis, photoelectron spectrometry and infra red spectroscopy. A layered structure in which the hafnium and phosphorus atoms are disposed in such a way as to form zeolitic-type cavities is suggested. The reversibility of the exchange with respect to sodium ions is discussed and can be related to the water content of the exchanger.